A wide variety of end products are manufactured from metal sheet stock, such as aluminum or stainless steel sheet stock. For example, beverage cans and various automotive parts such as radiator components and mufflers represent such products. Typically, a rolling mill produces relatively large diameter rolls of sheet stock that can vary in thickness and width. An individual strip of sheet stock can be hundreds or even thousands of feet long. The rolls of sheet stock are shipped to a processing plant where the strip is cut to the desired width and length. This product is wound into rolls which are shipped to another processing plant where the material is formed into the shape of the particular end product.
The rolls of sheet stock received from the rolling mill are placed on mandrels for processing. If it is necessary to create multiple strips of sheet stock from the initial roll, the sheet stock is typically fed to a machine containing upper and lower arbors disposed in close proximity to one another, with each arbor including rotary blades. Each rotary blade of the upper arbor is laterally spaced by a relatively small distance from the corresponding rotary blade of the lower arbor, with this lateral spacing resulting in the width of a slit between adjacent strips of material. Many strips can be cut from a single width of sheet stock and the width of a given strip can be relatively small, for instance to accommodate the ultimate manufacture of top tabs of metal cans used to contain beverages. The strip or strips of sheet stock are then processed further, including cutting the strips to the desired length.
It is necessary to very accurately measure the width of each strip and the thickness of each strip, typically at multiple locations across the width of the strip, for each roll of sheet stock. For instance, the manufacturer of an end product may require the thickness measurement of each strip of sheet stock to be accurate within plus or minus 0.0003 inch.
The necessary width and thickness measurements of the sheet metal strips can be obtained manually, with the sheet metal stationary, using a vernier caliper to obtain width measurements and a micrometer to obtain thickness measurements. As may be appreciated, this can be a time consuming process, particularly when considering the total time required throughout a day when many rolls of sheet stock are processed by a single production line, for example 50 or more rolls of sheet stock, and considering the fact that it may be necessary to measure the width of multiple strips for each roll and to measure the thickness at multiple locations for each strip. This translates into significant cost due to production line “down time” to obtain the necessary measurements.